City is dwarfed by London's main air hubs at Heathrow and Gatwick, but as the closest airport to the city centre it offers rapid access to the business districts of Canary Wharf (15 minutes) and the City of London (22 minutes).

It mostly serves European routes, although flights also run to New York. Increased traffic by business passengers pushed traveller numbers up to 4.3 million last year, up 18 percent from 2014.

But its development plans, which include the construction of a new taxiway for aircraft, were vetoed last year by London mayor Boris Johnson.

The project aimed to raise the hub's capacity to 6.5 million passengers a year by 2023.

GIP also owns London Gatwick and Edinburgh Airport in Scotland, which are not involved in the sale.